In the published French Pat. No. 2,294,535, filed Dec. 10, 1974 and to which correspond U.S. Pat. No. 4,078,183 granted Mar. 7, 1978, there has been described a control device, of the relay type, i.e. able to carry out switching, comprising three mechanical elements one of which is mobile in relation to the two others, characterised by the fact that these three mechanical elements are formed, on the one hand, by two control electrodes between which can be applied a predetermined potential difference and, on the other hand, an electret formed by an insulating piece carrying positive electric charges and/or negative electric charges, the algebraic sum of which is different from zero.
The mobile element could be formed either by the electret or by a control electrode.
Such a device may assume at least two positions, at least one of these positions being stable.
Different embodiments for forming electrical, optical or pneumatic switching devices for monostable or bistable operation have been desdribed in the above-cited French application.
U.S. Pat. Application Ser. No. 863,675, filed Dec. 23, 1977, which corresponds to French Patent Application of Addition No. 76 39795 filed Dec. 31, 1976, discloses a matrix of such control devices.